diff --git a/src/diffusers/models/autoencoders/autoencoder_kl_wan.py b/src/diffusers/models/autoencoders/autoencoder_kl_wan.py
index fe00d8c078ff..c27c12c6f648 100644
--- a/src/diffusers/models/autoencoders/autoencoder_kl_wan.py
+++ b/src/diffusers/models/autoencoders/autoencoder_kl_wan.py
@@ -748,6 +748,12 @@ def __init__(
         # The minimal distance between two spatial tiles
         self.tile_sample_stride_height = 192
         self.tile_sample_stride_width = 192
+        
+        # Precompute and cache conv counts for encoder and decoder for clear_cache speedup
+        self._cached_conv_counts = {
+            'decoder': self._count_conv3d_fast(self.decoder),
+            'encoder': self._count_conv3d_fast(self.encoder)
+        }
 
     def enable_tiling(
         self,
@@ -801,18 +807,12 @@ def disable_slicing(self) -> None:
         self.use_slicing = False
 
     def clear_cache(self):
-        def _count_conv3d(model):
-            count = 0
-            for m in model.modules():
-                if isinstance(m, WanCausalConv3d):
-                    count += 1
-            return count
-
-        self._conv_num = _count_conv3d(self.decoder)
+        # Use cached conv counts for decoder and encoder to avoid re-iterating modules each call
+        self._conv_num = self._cached_conv_counts['decoder']
         self._conv_idx = [0]
         self._feat_map = [None] * self._conv_num
         # cache encode
-        self._enc_conv_num = _count_conv3d(self.encoder)
+        self._enc_conv_num = self._cached_conv_counts['encoder']
         self._enc_conv_idx = [0]
         self._enc_feat_map = [None] * self._enc_conv_num
 
@@ -1083,3 +1083,8 @@ def forward(
             z = posterior.mode()
         dec = self.decode(z, return_dict=return_dict)
         return dec
+
+    @staticmethod
+    def _count_conv3d_fast(model):
+        # Fast version: relies on model.modules() being a generator; avoids Python loop overhead by using sum + generator expression
+        return sum(isinstance(m, WanCausalConv3d) for m in model.modules())